<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
        li{
            list-style-type: none;
        }
        .box{
            width: 250px;
             margin: 100px auto;
        }
        .box li{
            float: left;
            width: 24px;
            height: 24px;
            background-color: pink;
            margin: 15px;
        }
        img{
            width: 24px;
            height: 24px;
        }

    </style>
</head>
<body>
      <div class="box">
            <ul>
                <li><img src="img/1.jpg"></li>
                <li><img src="img/2.jpg"></li>
                <li><img src="img/3.jpg"></li>
                <li><img src="img/4.jpg"></li>
                <li><img src="img/5.jpg"></li>
                <li><img src="img/6.jpg"></li>
            </ul>
      </div>     

    <script>
          var lis = document.querySelectorAll("li");
          for(var i=0;i<lis.length;i++)
          {
              var index= i*44;
              lis[i].style.backgroundPosition="0"+index+"px";
          }
    </script>
</body>
</html>